Printing for Transparency

Natural (un-dyed) PLA is a translucent material, however, some students want to achieve a more transparent effect. These guidelines are aimed at helping students design with this in mind.

0.0 Clear Prints

Figure 0.0 - Rock, Rosie Gunzberg, printed with 0% infill in Natural PLA

Clear Prints may be extremely fragile and require special design considerations but have an aesthetic that can be hard to mimic with other materials and fabrication methods.

1.0 Factors which will Influence Transparency

1.1 Infill

Infill is necessary for parts with a roof structure which has internal overhanging elements. Infill density is the primary source of strength for FDM prints. An increased density will result in a stronger part, but will increase the part's opacity. If the part has no overhanging internal elements, it can be printed with 0% infill density. (Figure 1.1 shows the result of printing with 1 shell and 0% infill density)

Figure 1.1 - Printing with 0% Infill can result in small surface imperfections

1.2 Shells and Wall Thicknesses

Shells are the outer layers of a print. Using balanced settings, a print will use two shells. Having two shells allows the printer's mistakes due to under-extrusion to become less noticeable.

The greater the number of shells, the more opaque a print will be, but the cleaner the result.

As the Makerbots use a 0.4 mm nozzle, shells are generally 0.4 mm in thickness. Having air in between these layers of plastic can increase the opacity of a print. If designing purely for transparency, this means that plane objects should be designed at a total thickness of 0.8 mm (see figure 1.2). Students should note that these prints will be extremely fragile and may be difficult to remove from the rafts.

Figure 1.2 - Designing wall thicknesses based on nozzle size

1.3 Extruder Temperature

A slightly hotter extrusion temperature (217°) is recommended for getting a more transparent, less yellow colour using natural PLA. The default printing temperature is 215°. Do not recommend going any higher than this temperature.

Figure 1.3 - Comparison of two simple parts printed at 215° (left) and 217° (right)

Students should try not to exceed a temperature of 217°C

2.0 Designing for Transparency

2.1 Most Transparent: No Infill, One Shell

These settings are most appropriate when strength is not required and students are happy for somewhat rough surface finish

Feature

Recommended Setting

Wall Thickness (Design Requirement)

0.4 mm

Shells

1 Shell

Extrusion Temperature

217°

Infill Density

0%

Floor Thickness

Default

Roof Thickness *

Default

* Students need to be aware that if printing with no infill, roofs are only printable over walls. If there are any overhanging horizontal elements, the print will fail.

2.2 Second-Most Transparent: No Infill, Two Shells

These settings provide a slightly less transparent, but slightly more sturdy, cleaner finish to parts.

Feature

Recommended Setting

Wall Thickness (Design Requirement)

0.4 mm

Shells

2 Shells

Extrusion Temperature

217°

Infill Density

0%

Floor Thickness

Default

Roof Thickness

Default

* Students need to be aware that if printing with no infill, roofs are only printable over walls. If there are any overhanging horizontal elements, the print will fail.

2.3 Third-Most Transparent: 7% Infill, Two Shells

These settings provide far more sturdy and clean finish to parts, but these parts are the least transparent of all options.

Feature

Recommended Setting

Wall Thickness (Design Requirement)

0.4 mm

Shells

2 Shells

Extrusion Temperature

217°

Infill Density

7%

Floor Thickness

Default

Roof Thickness

Default